ted States Secret Service officers were called in to aid, yet it was Captain Jack and his friends who contributed to the full success of the government sleuths. At this period of his career Captain Jack's greatest dangers came through the wiles of charming women spies, especially one beautiful young Russian woman, Mlle. Sara Nadiboff, easily the most clever of all international spies. Yet the cleverness of the submarine boys carried them successfully, and with highest honor, through the gravest situations in their eventful, young careers.

Just at this particular time the young men had been going through dull days. Beyond the fact of the mere presence of the heavily charged torpedoes at the shipyard there had been nothing like excitement, for some time. This dullness, however, was destined to turn, suddenly, into the most intense and exciting activity.

As Jack pushed open the outer door of the office building of the shipyard, Jacob Farnum, the owner, happened to be bustling through the corridor.<